Update minimum cattrs version (#13223)

Fixes error on Python 3.9

(cherry picked from commit 9c0a5df222)

setup.cfg

@@ -89,7 +89,7 @@ install_requires =
     cached_property~=1.5
     # cattrs >= 1.1.0 dropped support for Python 3.6
     cattrs>=1.0, <1.1.0;python_version<="3.6"
-    cattrs>=1.0, <2.0;python_version>"3.6"
+    cattrs~=1.1;python_version>"3.6"
     colorlog==4.0.2
     connexion[swagger-ui,flask]>=2.6.0,<3
     croniter>=0.3.17, <0.4